Lab 1

Question 1

In liquid cultures as we work with in class , what is main factor that causes E.coli bacteria cell to slow down and eventually all but stop their growth?

Answer 1

Nutrient Depletion

Question 2

What did we do in class to our stock E.coli cultures to promote the resumption ……….and how did that class address the issues described in (A) above ?

Answer 2

We are use LB to our stock E.coli and diluted cells into fresh medium to feed more nutrients

Question 3

Draw a generic bacteria growth curve as it would appear on semilog paper and label frour of the growth “ phases “

Answer 3

Question 4

How do the antibiotics “Ampicillin” and “Kanamycin” metabolically ?

Answer 4

Ampicillin
Blacks cell wall biosynthesis

Kanamycin
Interferes with protein synthesis (= translation)

Question 5

What is the definition of the “ cell population doubling time” (t-D) of a baxterial culture?

Answer 5

described as the time it table for the bacteria to divide into two cells.

Question 6

Can you estimate ( approximately, not exactly) the t-D of the culture whose growth curve is illuminated in the above …..?

Answer 6

110- 90 =20 minutes

Approximately 20 minutes is the doubling time

Question 7

Which type of negative metabolic effects ( mechanism of action) do the antibiotics Ampicillin and Kanamycin have on E.coli ?

Answer 7

Ampicillin
1. Interferes with cell wall biosynthesis

Kanamycin
1. Affects protein translation aideliry

Question 8

Which method of measuring cell density best reflects the Actual concentration of live cells able to replicate their DNA and divide….and plating ? Explain

Question 9

What are two methods we used in class that capable of monitoring changes in liquid culture bacterial cell density ?

Answer 9

spectrophotometer

dilution series and plating

Question 10

which of these methods more accurately tracks” viable” cell (cells capable of reproducing) and why is this so ?

Answer 10

dilution series because from colonies